/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.api.java.hadoop.mapreduce.utils;

import org.apache.flink.annotation.Internal;
import org.apache.flink.configuration.GlobalConfiguration;

import org.apache.hadoop.conf.Configuration;

import java.util.Map;

/** Utility class to work with next generation of Apache Hadoop MapReduce classes. */
@Internal
public final class HadoopUtils {

    /**
     * Merge HadoopConfiguration into Configuration. This is necessary for the HDFS configuration.
     */
    public static void mergeHadoopConf(Configuration hadoopConfig) {

        // we have to load the global configuration here, because the HadoopInputFormatBase does not
        // have access to a Flink configuration object
        org.apache.flink.configuration.Configuration flinkConfiguration =
                GlobalConfiguration.loadConfiguration();

        Configuration hadoopConf =
                org.apache.flink.api.java.hadoop.mapred.utils.HadoopUtils.getHadoopConfiguration(
                        flinkConfiguration);

        for (Map.Entry<String, String> e : hadoopConf) {
            if (hadoopConfig.get(e.getKey()) == null) {
                hadoopConfig.set(e.getKey(), e.getValue());
            }
        }
    }

    /** Private constructor to prevent instantiation. */
    private HadoopUtils() {
        throw new RuntimeException();
    }
}
